(a) Field of the Invention
The present invention relates to a method of manufacturing a thin film transistor array panel, and, in particular, to a method of manufacturing a thin film transistor array panel having a polycrystalline silicon semiconductor.
(b) Description of the Related Art
A thin film transistor (“TFT”) array panel is used as the substrate of a data driver circuit configured to individually drive each pixel in a flat panel display composed of a plurality of pixels, such as a liquid crystal display (“LCD”) or an organic light emitting device (“OLED”).
A liquid crystal display (“LCD”) includes two panels (e.g., substrates) each provided with field-generating electrodes (such as pixel electrodes and a common electrode), with a liquid crystal (“LC”) layer interposed therebetween. The LCD displays images by applying voltages to the field-generating electrodes to generate an electric field across the LC layer, which controls the orientations of LC molecules in the LC layer to adjust transmittance of incident light through the two panels.
Generally, the TFT includes a semiconductor made of amorphous silicon or polycrystalline silicon.
Amorphous silicon is widely used in a display device having glass with a melting point which is low, since an amorphous silicon film can be fabricated at a relatively low temperature.
For crystallizing amorphous silicon to form a polycrystalline silicon film, either an excimer laser anneal (“ELA”) process, a chamber anneal process, a sequential lateral solidification (“SLS”) process, a metal-induced crystallization (“MIC”) process, and a metal-induced lateral crystallization (“MILC”) process are used.
The MIC or MILC processes form the polycrystalline silicon film by contacting portions of the amorphous silicon film with a metal. At this time, metal atoms move into the amorphous silicon film to perform crystallization of amorphous silicon. The MIC and MILC processes have advantages which include low cost and TFTs obtained with uniform characteristics, as compared with the remaining processes using a laser.
However, the MIC or MILC processes require forming of a metal film on the amorphous silicon film, and in particular, the MILC process requires an additional patterning process. Furthermore, after the crystallization, the metal atoms remain in channel regions or junction region between source and drain regions of TFTs due to the metal atoms moving into the amorphous silicon film and use of a catalyst. Thereby, leakage current occurs as a result of the remaining metal atoms between the source and drain regions of the respective TFTs.